We propose a volumetric formulation for computing the Optimal Transport problem defined on surfaces in $\mathbb{R}^3$, found in disciplines like optics, computer graphics, and computational methodologies. Instead of directly tackling the original problem on the surface, we define a new Optimal Transport problem on a thin tubular region, $T_{\epsilon}$, adjacent to the surface. This extension offers enhanced flexibility and simplicity for numerical discretization on Cartesian grids. The Optimal Transport mapping and potential function computed on $T_{\epsilon}$ are consistent with the original problem on surfaces. We demonstrate that, with the proposed volumetric approach, it is possible to use simple and straightforward numerical methods to solve Optimal Transport for $\Gamma = \mathbb{S}^2$.

翻译：我们提出了一种体积公式化方法来计算定义在$\mathbb{R}^3$中曲面上的最优输运问题，该问题常见于光学、计算机图形学和计算方法学等领域。不同于直接在曲面上处理原始问题，我们在曲面邻近的薄管状区域$T_{\epsilon}$上定义了一个新的最优输运问题。这种扩展为笛卡尔网格上的数值离散提供了更强的灵活性和简洁性。在$T_{\epsilon}$上计算得到的最优输运映射和势函数与原始曲面问题保持一致。我们证明，通过所提出的体积方法，能够使用简单直接的数值方法求解$\Gamma = \mathbb{S}^2$上的最优输运问题。